Synthesis and characterization of a new microporous aluminophosphate with levyne structure in the presence of HF

Microporous crystal of the aluminophosphate analogue with levyne structure (AlPO₄-35) were successfully synthesized in the presence of HF using tropine hydroxide as an organic template. Generally, under a starting composition of Al₂O₃:P₂O₅:1.5 Tropine:HF:200 H₂O, the crystallization product is the microporous material AlPO₄-5; a pretreatment at 100 °C for 10 h leads to the formation of the aluminophosphate analogue with levyne structure (AlPO₄-35), although the starting composition is the same. Observation of the pretreatment at 100 °C by X-ray powder diffraction showed that poorly crystalline AlPO₄ · 2H₂O (metavariscite/variscite) plays an important role as reactive intermediate in the synthesis of microporous AlPO₄-35.